Diathermy plate electrode

ABSTRACT

This invention relates to a plate electrode for use in surgical diathermy or electrosurgical apparatus. The electrode is a thin flexible sheet of metal foil backed by a flexible film of plastics material.

United States Patent Frisbiem, ..l74/l l7 Blackett [4 1 May 16, 1972 541DIATHERMY PLATE ELECTRODE 3,547,103 12/1970 Paine..... ..l28/2.06 [72]Inventor: I John HaroldBlackett, London, England 22: [73] Assignee:Matbum (Holdings) Limited, London, En- 1,353,814 1932 Huth gland1,889,272 11/1932 Zerne ....l28/416 1,662,446 3/1928 Wappler ....128/4l6[221 2,843,829 7/1958 Slate ..336/200 FOREIGN PATENTS OR APPLICATIONS 419 24 Fmig 111907 122m A .25,1969 G tB't' ..21,180 69 pr M am y I vOTHER PUBLICATIONS 52 us. c1. ..l28/416, 174/117 FF, 336/232 & 5101 e riv01, 7, pp. 341- 343, Dec. 28, [5 1] Int. Cl. ..A61nl/06 9 3 [58] Fieldof Search... 1 28/416, 2.06 E, DIG. 4, 303.13;

1 17 1 17 1 17 232 Primary Examiner-Kyle L. Howell Attorney-William R.Liberman [56] References Cited [57] ABSTRACT UNITED STATES PATENTS Thisinvention relates to a plate electrode for use in surgical 1,989,2821/1935 Klmble et a1 ..128/416 diathermy or electrosm-gical apparatus Theelectrode is a hi 315431760 12/1970 Bolduc flexible sheet of metal foilbacked by a flexible film of plastics 3,572,322 3/1971 Wade material3,229,030 1/1966 Baermann... 2,628,998 2/ l 953 6 Claims, 2 DrawingFigures DIATHERMY PLATE ELECTRODE BACKGROUND OF THE INVENTION Diathermyis a process by which heat is developed in the human body by the passageof a high frequency alternating electric current. A typical surgicaldiathermy apparatus has two electrodes. One of these electrodes iscalled the active electrode and is the electrode used for cutting andcoagulating the tissue. This electrode has a very small surface area andthe current passing from this electrode to the' tissues has an intenseheating effect. The other electrode is necessary to complete theelectrical. circuit and is termed the indifferent ground or plateelectrode. This electrode is muehlarger in area than the activeelectrode in order to reduce the, current intensity and therefore itsheating effect. In order to prevent the occurrence of burns, it isimportant that a high proportion of the area of the plate electrode ismaintained in good electrical contact with the skin.

Plate electrodes are usually of lead or stainless steelwhich can bemoulded to conform to the sites of application to the patients, usuallythe thighs. To maintain good contact with the skin, the plate electrodeis. placed in a gauze bag and dipped in saline solution before use.Conductive creams or jellies may also be used in the case of stainlesssteel plates. When a'lead plate has been bent a number of times, ittends to become corrugated, so that the larger area of contact isreduced to a number of ridges, and this can lead to burns at'the site ofthe plate electrode. Such burns may be very serious.

The conventional plate electrodes also suffer from other disadvantages.Thus, the connecting lead to the diathermy apparatus has to be fitted onto'the plate with a connector or attachment of some sort, and thisalways involves the possibility of bad electrical contact or breakage,which may also result in the patient being burnt. The high thermal massof the conventional plates in particular large, thick lead plates,combined with the cooling effect of the saline, can produce a seriousfall in body temperature in the treatment of infants and young children.Furthermore, lead plates are very heavy, and there is always the dangerthat they will slip out of place if notbound firmly to the patient.

An object of the present invention is to provide a plate electrode whichavoids the disadvantages of known plate electrodes.

SUMMARY OF THEINVENTION A plate electrode according to the presentinvention comprises a thin and flexible sheet of metal foil backed by aflexible film of plastics material. The thickness of the metal foil lar,or circular. Different shapes may be more convenient for certain siteson the body, and for different methods of attachment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an electrodeaccording to the invention, and

FIG. 2 is a section to a greatly exaggerated scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrode 1 is of circularshape with a diameter of about prevent' accidental contact with otherapparatus or with the 15 centimeters. The electrode consists of a thin,flexible and conductive metal foil with a backing 2 of thin flexibleplastics material. Such an electrode has the great advantage overconventional plate electrodes that it is very flexible and alwaysprovides excellent electrical contact with the skin of the patient overthe whole surface area of the electrode. The electrode plate is useddry, eliminating the need of saline contact solution or jelly. Theelectrode is also very light in weight and may be easily and securelyfitted to the patient by means of an adhesive plaster or a bandage orthe like.

The metal foil l canbe of any convenient conductive material. It may,for example, be of copper or aluminum or stainless alloy. The backing 2may be or any suitable flexible plastics film such as polyvinylchloride, polyethylene, or a polyester such as that known under theregistered trade mark of Mylar.

The electrode is preferably provided with two integral flexibleconductor leads 3 or 4. More than two leads canbe provided if desired.Where two leads are provided, both leads are made of flexible metal foilbacked by flexible plastics film and the conductive metalfoil may have acovering 5 of insulating material. The insulating covering 5 to theconductor leadmay conveniently be of any flexible plastics'film'material such as polyvinyl chloride, polyethylene or a polyester, or itmay be of a plastics coating applied in liquid form.

The purpose of a second conductor lead is to enable the electricalcontinuity of the plate electrode to be monitored continuously, bypassing a small electrical current down one of theconductors to theplate electrode and back via theother conductor through a currentsensing circuit, which may be arranged to provide a warning signal ifthere is a discontinuity in the plate circuit. This current is asecondary current which is not in any way connected with the highfrequency diathermy current.

The leads 3 and 4 have terminal portions6 and 7.

The plate electrode may be made by first producing a laminate consistingof a flexible metal foil backed by the flexible plastics material afterwhich the electrode and, if desired, its lead is produced simply bycutting it out of the laminated sheet. However, the electrode and itslead are advantageously manufactured by printed circuit techniques. Forexample the metal foil'of the laminate can be etched to the desiredshape, after first covering the required metal area with an etchresistant coating. i

An advantageof using an etching technique instead of the mechanicalcutting is that as shown in the drawing, a border 8 of non-conductingplastics material is left surrounding the metal foil of thejelectrodeand the integral lead. This provides an insulated edge to'the leadconductor or conductors to body of the patient.

It has been found both convenient and economical to produce theconductor leads 3 and 4 in the form of a coil or coils surrounding theplate electrode; In such a case, a portion of the plastics film of thebacking may extend between adjacent coils and may be cut in a continuousspiral which upon extension forms a longitudinally. extending lead ofsufficient length (approximately 2 meters) to reach from the diathermygenerator to the patient. Preferably however, thin radial portions orbridges" of the plastics film may be left between adjacent turnssufficient to hold the coils in position for packing, but which willbreak if pulled, to allow the lead to be extended.

After the electrode and its lead has been produced in this manner, theymay be backed by a suitable material to keep the lead in position forpacking and storage purposes until the electrode is required for usewhen the backing material is removed to allow the leads to be extended.

What we claim is:

1 A'plate electrode device for use in surgery comprising a thin flexiblemetal foil sheet electrode, a thin flexible plastic' leads integrallyformed at their innerends in one piece with said metal foil sheet andextendable therefrom, said conductor leads being spaced from one anotherthroughout their entire length, a thin flexible electricallynon-conductive backing superimposed on one face of and joining said pairof metal foil bands and an electrically insulating layer covering theother face of said bands.

2. The plate electrode device of claim 1 wherein said sheet 5 electrodeand bands are substantially coplanar and said pair of bands are spirallywound about said electrode.

3. The plate electrode device of claim 2 wherein the confronting edgesof successive convolutions of said band pair are

2. The plate electrode device of claim 1 wherein said sheet electrodeand bands are substantially coplanar and said pair of bands are spirallywound about said electrode.
 3. The plate electrode device of claim 2wherein the confronting edges of successive convolutions of said bandpair are separably joined.
 4. The plate electrode device of claim 1including electrical coupling elements connected to the outer ends ofsaid bands.
 5. A plate electrode as claimed in claim 1, wherein theelectrode is of aluminum foil and the backing is of a polyester.
 6. Aplate electrode as claimed in claim 1 wherein the electrode is of copperand the backing is of polyester.